1. Field of the Invention
The invention relates generally to printheads in printing devices, and, more particularly, to a nozzle plate for bonding to a chip for configuring a printhead of a printing device.
2. Description of the Related Art
Printing devices commonly referred to as printers, are widely used in offices, in homes and in business enterprises. The printing devices output information displayed on a screen of a data processing device onto a media sheet such as a sheet of paper. The information may be output onto the media sheet by impacting desired information elements, such as characters, onto the media sheet, or alternatively, the printing devices may propel droplets of liquid medium, such as ink, onto the media sheet for outputting the information onto the media sheet. Commonly used printing devices, such as inkjet printers, propel ink droplets onto the media sheet for transferring the information onto the media sheet. The inkjet printers typically use print cartridges having printheads for directing the ink droplets onto the media sheet in patterns corresponding to the information to be printed onto the media sheet.
A typical print cartridge of an inkjet printer includes an ink container and a printhead. The printhead includes a chip and a nozzle plate bonded to the chip. The nozzle plate includes a plurality of nozzle holes. During a printing operation, the printhead is moved relative to the media sheet and the ink droplets are released through nozzle holes of the plurality of nozzle holes for transferring the information onto the media sheet.
Referring now to drawings and more specifically to FIG. 1, a cross-sectional view of a portion of a prior art nozzle plate 10 attached to a chip 12 prior to bonding nozzle plate 10 to chip 12 is depicted. Nozzle plate 10 includes a substrate layer 14 and an adhesive layer 16. Adhesive layer 16 comprises a first surface (not shown) attached to substrate layer 14 and a second surface (not shown) attached to a planarizing layer 18 for attaching nozzle plate 10 to chip 12. Planarizing layer 18 provides a planar surface on chip 12 for attaching nozzle plate 10 to chip 12. A plurality of nozzle holes, such as a nozzle hole 20a and a nozzle hole 20b, may be perforated into substrate layer 14 and adhesive layer 16. Nozzle holes, such as nozzle hole 20a and nozzle hole 20b, may hereinafter be collectively referred to as a plurality of nozzle holes 20 (not shown). It will be evident to those skilled in the art that FIG. 1 depicts the cross-sectional view of the portion of nozzle plate 10 and that nozzle plate 10 includes plurality of nozzle holes 20 (not shown) perforated in substrate layer 14 and adhesive layer 16.
Each nozzle hole of plurality of nozzle holes 20 configures an ink flow chamber, such as an ink flow chamber 22a and an ink flow chamber 22b, for receiving ink from an ink container (not shown). A structural configuration, i.e., configuration of wall, of each ink flow chamber defines a flow-feature for respective nozzle hole for directing the ink towards an opening of the respective nozzle hole. The flow-feature for the each nozzle hole is configured to be substantially symmetrical about a central axis of the each nozzle hole for facilitating movement of ink droplets towards the opening. For instance, the flow-feature associated with nozzle hole 20a may be substantially symmetrical about a central axis 24a for facilitating movement of the ink droplets towards an opening (not shown) of nozzle hole 20a. 
Chip 12 includes a plurality of energizing elements such as an energizing element 26a and an energizing element 26b. Energizing elements, such as energizing element 26a and energizing element 26b, will hereinafter be collectively referred to as a plurality of energizing elements 26 (not shown). An example of an energizing element of plurality of energizing elements 26 may be a resistive heating element. Chip 12 is attached to nozzle plate 10 prior to bonding chip 12 to nozzle plate 10, such that the each nozzle hole is associated with an energizing element. For instance, nozzle hole 20a is associated with energizing element 26a, and, nozzle hole 20b is associated with energizing element 26b. 
Prior to attaching nozzle plate 10 to chip 12, nozzle plate 10 may be prestretched, i.e., aligned such that the each nozzle hole of plurality of nozzle holes 20 is configured to align a central axis of the each nozzle hole at a pre-defined distance from a central axis of the energizing element of the plurality of energizing elements associated with the each nozzle hole. On aligning nozzle plate 10 with chip 12, nozzle plate 10 may be bonded to chip 12 using one or more thermal processes such as Thermal Compression Bonding (TCB), bake and the like. Nozzle plate 10 bonded to chip 12 is depicted in FIG. 2.
FIG. 2 depicts a schematic depiction of a cross-sectional view of the portion of prior art nozzle plate 10 bonded to chip 12. Prestretching nozzle plate 10 prior to bonding to chip 12 may substantially align a central axis of the each nozzle hole with a central axis of a corresponding energizing element during the bonding of nozzle plate 10 to chip 12, such that the each nozzle hole may be centered over the corresponding energizing element. For instance, an alignment of central axis 24a of nozzle hole 20a is substantially aligned with a central axis (not shown) of energizing element 26a. During bonding of nozzle plate 10 with chip 12 using thermal processes such as TCB, bake and the like, substrate layer 14 and chip 12 undergo varying levels of expansion. Adhesive layer 16 which is attached to substrate layer 14 at the first surface and attached to chip 12 at the second surface is forced to stretch and conform to the varying levels of expansion, resulting in asymmetrical flow-features for ink flow chambers associated with plurality of nozzle holes 20. For instance, flow-features for ink flow chambers, such as ink flow chamber 22a and ink flow chamber 22b corresponding to nozzle hole 20a and nozzle hole 20b, respectively, are asymmetrical respect to respective central axes, on bonding nozzle plate 10 to chip 12.
The asymmetrical flow-features for the each nozzle hole may impact a directionality of ink droplets to be ejected from of plurality of nozzle holes 20. Moreover, asymmetrical flow-features may also result in expanding a swath area, i.e., an area traced on the media sheet by the printhead, during a particular unidirectional scan of a printhead onto the media sheet.
Based on the foregoing, there is a need for compensating for deformation of a nozzle plate during the bonding of the nozzle plate to a chip. Further, there exists a need for configuring a nozzle plate with improved post-bonding symmetry, i.e., substantially symmetrical flow-feature for nozzle holes, subsequent to the bonding of the nozzle plate to the chip. Furthermore, there exists a need to substantially reduce swath area expansion resulting from deformation caused to a nozzle plate during the bonding of the nozzle plate to the chip.